Pump



Sept. 13, 1949. JOHNSON 2,481,754

PUMP Filed July 27, 1946 2 Sheets-Sheet 1 E T E 1.5.41.

IN V EN TOR.

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A TTORNEY P 1949' L. E. JOHNSON 2,481,754 l PUMP Filed July 27, 1946 2Sheets-Sheet 2 i l I v IN V EN TOR.

L/ig J E z/o/mson Patented Sept. 13, 1949 PUMP Lloyd E. Johnson, Peoria,111., assignor to Caterpillar Tractor 00., San Leandro, Calii'., a cor.-

poration of California Application July 2'7, 1946, Serial No. 686,770 3Claims. (Cl. 103161) The present invention relates to rotary pumps andis disclosed herein in its application as a fuel pump for an internalcombustion engine, though its adaptability to other uses will beapparent from the following detailed disclosure.

It is an object of the invention to provide an improved pump of therotary-type in which radially disposed pump plungers reciprocate as aresult of the differential spacing which occurs due to rotation ofeccentrically disposed members. Other objects of the invention are toprovide improved driving connectionsfanti-friction means, and sealingmeans for pumps of this kind; Further and more specific objects andadvanta es of the invention are made apparent in the followingspecification wherein reference is made to the accompanying drawings.

' In the drawings:

Fig. 1 is a longitudinal sectional view of a pump embodying the presentinvention illustrated as driven by the cam shaftof an internalcombustion engine;

Fig. 2 is a horizontal sectional view of a part of the pump shown inFig. 1 and taken on the line 11-11 of Fig. 1;

Fig. 3 is a transverse section taken on the line III-III of Fig. 1;

Fig. ,4 is an isometric view of one of the plungers of the pump; and

Fig. 5 is an isometric view of one of a pair of springs which form partsof the pump.

The pump as shown in Figs. 1 and 2 is disposed in a housing III which isillustrated as secured to the, fuel pump housing of an internalcombustion engine of the compression ignition type. A portion of thefuel pump housing is shown at II and the pump housing It is shown assecured thereto by means of cap screws i2. This positioning of the pumpenables it to be driven by the fuel pump cam shaft, a portion of whichis shown at [3 of the engine, though other drive connections will bemade when the pump is used in a different en vironment.

Within the housing II a rotary cup-shaped member 14 is secured to theend of the shaft l3 by which it is driven by means of cap screws It. Astationary shaft or pump stator i1 is supported by the housing ill in amanner presently to be described, and extends into the housing tosupport a rotatable cylinder block it. The block 13 has four equallyspaced radially disposed cylins der bores I3, each of which carries apump plunger 20 for reciprocation therein in a radial direction. Theouter ends of the pump plungers che se the inner periphery of the rotarycup I4,

each plunger carrying a hardened ball 2| which contacts a pad 22 formedinside the cup. The

pads 22 are equally spaced about the inner pe- 'through transverse bores25 of the plungers 20.

Each spring acts with an opposed pair of plungers normally to urge themoutwardly with their balls 2i in contact with the pads 22. The sides ofthe cylinders in the block member iii are notched for reception of thesprings as indicated at 26 to permit inward movement of the plungers.The springs 23 are provided with loops intermediate their ends and theloop 21 on one of the springs is engaged during assembly in a slot 28(see Fig. 1) formed in the wall of the rotary cup It. This engagement ofthe spring loop 21 with the rotary cup forms a driving connectionbetween the cup and the rotary cylinder block so thatthese parts rotatein unison. The axis of the stator I'I about which the cylinder blockrotates is eccentrically disposed with relation to the cup H so thatupon rotation of these members the plungers 20 which are normally urgedoutwardly are each moved through a complete reciprocal stroke once foreach rotary cycle.

The stator I! has an enlarged head 30 atits outer end which is held in asuitable recess formed in the housing Iii by means of a cap member 3|(see Figs. 1 and2) secured in place by cap screws 32. Intake anddischarge fittings 33 and 34 respectively are connected with the cap 3iand communicate through passages 35 and 36 therein with longitudinalpassages 31 and 38 in the stator IT. The passages 31 and 38 intersectnotches 39 and Ill respectively cut in opposite sides of the stator andthe position of the stator is such that each of the four plungers 20moves outwardly or on a suction stroke as it passes the notch 39 whichcommunicates with the intake passage and inwardly or on a pressurestroke as it passes the notch 40 which communicates with the dischargepassage. Consequently, the pump is constantly drawing liquid in throughthe intake passage and constantly pumping it out through the dischargepassage as long as it continues in rotation. The stator I I is held inits proper fixed position by apin l2 shown in Fig. 1 which passesthrough a notch in its head 30 and eruiters a receiving bore in the endof the housing I The rotary cylinder block I3 is held against endwiseremoval from the stator II by a washer so 43 and snap ring 44, both ofwhich are enclosed 3 by a cup 45 preferably press fitted over anextended cylindrical part of the cylinder block and sealed around itsedges by a sealing ring 46. The opposite end of the rotary cylinderblock engages a shoulder 41 formed inside of the housing l0. Anytendency of the liquid being pumped to escape at the shoulder 41 iscounteracted by the fact that the intake passage "31 extends all of theway through the stator I! and communicates with the interior of the cap45 to create a reduced pressure therein tending to urge the cylinderblock by which the cap is carried to the right, as viewed in Fig. 1, orinto close contact with the shoulder 41. As a further precaution againstfuel oil escaping at this point, lubricating oil under pressure may bedirected througha line 48 which is connected with a bore 49 in the pumphousing I. The bore'49 communicates with a groove 50 which circumscribesthe stator 11, and drilled passages shown at in Fig. 1 communicatethelubricating oil under pressure to a groove 52 also circumscribing thestator l1 and establishing pressure between the relatively rotatingsurfaces of the stator and the clyinder block to oppose the pressure ofthe pumped oil tending to leak toward the shoulder 41.

The details of construction of theplungers 20 are best shown in Fig. 4wherein one of the plungers is shown as having an end 54 concavelyformed to correspond with the cylindrical shape of the stator 11. Thebore 25 which receives the end of the spring 23 is formed on an axisparallel to that from which the concave end 54 is cut so that the springserves to prevent rotation of the plunger in its cylinder and positionsthe plunger with its concave end in proper registry with the cylindricalsurface of the stator IT. The opposite end of each plunger is providedwith a cylindrical bore 55 intersecting its end and with a snap ringgroove 56 intersecting the bore 55. The bore 55 receives theanti-friction ball 2| which contacts the pad 22 as previously describedand permits slight movement of the ball necessary to maintain a contactpoint of low friction. A snap ring 51 shown in Figs. 1 and 3 is fittedinto each of the grooves 55 to prevent escape of the balls 2 I.

With the construction shown the simple spring members 23 serve as adriving connection between the rotary cup and the cylinder block andserve to urge the plungers outwardly with constant resilient tension aswell as to hold them against rotation in their respective cylinders. Thesimple construction of hte plungers and the cylinder block enables theparts to be lap fitted with ease to provide a pump capable of producinghigh' pressure. The possibility of leakage of the fuel oil being pumpedis very small but any oil which might leak through the joint formed atthe shoulder 41 would be received by the pump housing l0 and may bedrained into the crank case of the engine through a drain port such asindicated at 58.

4 I claim: 1. A pump comprising a stator having intake and dischargepassages, a cylinder block rotatable on the stator and carrying radiallyarranged reciprocable plungers cooperating with said passages, aneccentrically disposed rotary drive member surrounding the cylinderblock to limit outward movement of the plungers, and springs engagingopposed pairs of plungers to urge them outwardly into contact with thedrive member, one of said springs having a part engaging the drivemember to form a driving connection with the cylinder block.

2. A pump comprising a stator having intake and discharge passages, acylinder block rotatable on the stator and carrying radially arrangedreciprocable plungers cooperataing with said passages, an eccentricallydisposed rotary drive meniber surrounding the cylinder block to limitoutward movement of the plungers, each plunger having a transverseopening therein, and springs each having opposed ends engaging in theopenings of opposed plungers to urge the plungers outwardly and toprevent their rotation in the cylinder block one of said springs havingapart engaging the drive member to form a driving connection with thecylinder block.

3. A pump comprising a stator having intake and discharge passages, acylinder block rotatable on the stator and carrying radially arrangedreciprocable plungers cooperating with said passages, an eccentricaliydisposed rotary drive member surrounding the cylinder block to limitoutward movement of the plungers, each plunger having a transverseopening therein, and springs disposed exteriorly of the cylinder blockand each having opposed ends engaging in the openings of opposedplungers to urge the plungers outwardly and to prevent their rotation inthe cylinder block one of said springs having a part-engaging the drivemember to form a driving connection with the cylinder block.

LLOYD E. JOHNSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain Jan. 22, 1920

